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C2D Overclock Temps & Lapping

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October 7, 2007 9:56:47 AM

C2D Overclock Temps & Lapping

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Hi All,

Just a quick and hopefully simple question from a newby overclocker.

I've been overclocking my new E4400 chip on a shuttle barebones rig, which doesn't provide so many options for overclocking / temperature control.

I can easilly overclock the CPU on stock voltages (ex DDR) all the way to 3.2Ghz (stable) with 3.5Ghz passing post without extra power. My problem with all of this is temperature, or more importantly working out what temp things are actually running at.

I've read lots about tCoreMax, tCase etc and know the thermal specs for my proc, but I'm having problems interpreting the tools.

I'm running speedfan, coretemp, cpu-z to identify speeds and temps.

When idle, with fans on full, I'm getting tcase temps well below ambient at 1600Ghz. When I move up through the FSB range, my idle temp for tCase moves up to the 32 range. However, the core temps as read by Coretemp and SpeedFan don't move more than a couple of degrees at idle. Ie, they don't track. The Coretemps are reading more like 28C in speedfan and 40/42 in coretemp. Note that the coretemps on speedfan are usually the same for each core, where coretemp reads a 4C difference between cores. I thought that these were supposed to be reading the same temps. Could it be the cores have different hard coded thresholds from the factory, which coretemp is working from and not speedfan ?

As soon as I shove through a prime95 load, my tCase temp shoots up to the same levels or slightly higher than the coretemps. From what I've read, tCase should be approx 15C lower than the cores for my processor (L2 stepping).

My question is what temp should I use for assessing actual CPU temps to avoid frying my cpu. Speedfan Coretemps - 15C to give me a target tCase temp of around 50-55 ?

The bios always reports 35-38C in the health check section for idle, no matter what the clock speed etc.

All temps reported when Ambient was 22.4-22.7C.

From a lapping perspective, my E4400 is concave as you would expect. Not massively so, but considering the idle-load increase from 28-58 ( 30C which is more than it commonly should be ) am I making a good contact with the HSF/Spreader ? And therefore should I lap it ?

I'm running stock cooling (Shuttle ICE) with AS5 thermal paste. I've mounted the HSF a couple of times and found that the best approach to idle temps seemed to be when after spreading the paste with a knife across the HSF and mounting it and then pulling it off, cleaning the HSF and then remounting. Idle temps for tCase read much lower this way although load levels didn't seem all that affected. Note, I mounted with thin layer, thin line along cores as per AS instructions and a blob in the middle. They do have significant differences between mountings.

The other part of the equation for me is - silence. I want a quiet machine, so the overclock levels I will finally stay with will be dependant on the fan noise levels needed to maintain the safe temps. I'll re-enable C1E as well, but don't want to have a low speed clock below a reasonable performance. ie perhaps 300Fsbx6 - giving me 1.8Ghz throttled with demand capacity of 3Ghz. It will depend on how often the load gets up high enough for C1E to take the multiplier back up again.

So I want it all, but don't want to pay for it.

Over to the experts - how should I assess my temps and what is the max I should go for using the suggested temps.
October 10, 2007 6:03:52 PM

listen to coretemp. it doesnt matter if your cores are different temps. as for lapping your processor, dont do it. its never a good idea and if you dont break it the gains are not exceptional. lap your heatsink if you feel inclined to lap something. if you want higher clocks and lower temps move past the stock heatsink/fan. people tend to disagree on good temps but i'd recommend staying below 45 degrees C idle and no more than 53-54 degrees under max load. some people will say thats even too high but its just for guidance.
October 10, 2007 7:06:22 PM

Drew,

Just a little concerned at the temps you suggested. Coretemp doesn't read actual temperatures, but a temperature relative to the TJunctionMax that's shown above the temps right ?

Some numbers to ponder:

At ambient 24C with the case off and the hard drive mounted outside, with no external graphics card:

On 10x200 Stock settings for my E4400, with C1E disabled, running with FANS on minimum (1500RPM) coretemp reads a Core Temperature of 40/42 idle, 63C within 5 seconds of Prime95 load is applied.

On 10x200 Stock settings for my E4400, with C1E disabled, running with FANS on maximum (4000RPM) coretemp reads a Core Temperature of 37/40 idle, 58C within 5 seconds of Prime95 load is applied.

As you can see, none are within your recommended range and that's without the hardrive, graphics card present or restricted airflow from mounting the cover.

The temperatures as displayed on speedfan however for each core was 44C under load and 25C at idle, much more like the range you're offering and what I would expect with the case off and fans on max.

I'm using coretemp 0.95 for the measurements.

Additionally, when using the bios fan speed settings, all of the speed related settings ( excluding smartfan ) won't change from thier default to max before reaching 75C. By that time, it's a little late.

The confusion continues.
!